diff --git a/source/build/src/polymost.cpp b/source/build/src/polymost.cpp
index d71bcd126..f12c08142 100644
--- a/source/build/src/polymost.cpp
+++ b/source/build/src/polymost.cpp
@@ -2850,6 +2850,9 @@ static void polymost_domost(float x0, float y0, float x1, float y1, float y0top
         dm1.x = xbr;
     }
 
+    dm0.x -= DOMOST_OFFSET;
+    dm1.x += DOMOST_OFFSET;
+
     drawpoly_alpha = 0.f;
     drawpoly_blend = 0;
 
@@ -2923,6 +2926,14 @@ static void polymost_domost(float x0, float y0, float x1, float y1, float y0top
 
         float const rdx = 1.f/dx;
 
+        for (bssize_t i = 0; i < scnt; i++)
+        {
+            if (spx[i] < x0)
+                spx[i] = x0;
+            else if (spx[i] > x1)
+                spx[i] = x1;
+        }
+
         for (bssize_t z=0, vcnt=0; z<=scnt; z++,i=vcnt)
         {
             float t;